A huge wheat field circle suddenly appears in the playground after a snowfall. Who, what, and how did it happen? The "Deduction Trio" of the 4th grade class - Ama Tsujido, Roku Yuzuki, and Misuzu Kamiyama - are tasked by their class teacher, Ms. Mariko, to take action. The trio is tasked by class teacher Mariko to take action! Can you take on the challenge of the great detective Tsujido Tenma? What is the truth of the matter? Go to the book to collect clues and start your exciting deduction!